Fix equality comparator of super hash with nil (#30)

Fix an #<ArgumentError: odd number of arguments for Hash> exception.

Author: sobrinho

lib/dwolla_v2/super_hash.rb

@@ -6,7 +6,7 @@ class SuperHash < Hash
     include Hashie::Extensions::DeepFetch
 
     def == other
-      super(other) || super(self.class[other])
+      super(other) || other && super(self.class[other])
     end
   end
 end

spec/dwolla_v2/super_hash_spec.rb

@@ -22,4 +22,10 @@
     super_hash = DwollaV2::Util.deep_super_hasherize(hash)
     expect(super_hash).to eq hash
   end
+
+  it "== works with nil values" do
+    hash = { a: { b: { c: "d" } } }
+    super_hash = DwollaV2::Util.deep_super_hasherize(hash)
+    expect(super_hash).not_to eq nil
+  end
 end